What you want, if you want to use 540's are the crawler motors, 65 turn or even 85 turn, direct drive to the prop.
Courtesy of patmat2350
Integy Lathe
Motor (3 pole)___KV_____RPM on 12v
35T____________1730______20,760 (estimate)
45T____________1358______16,296
55T____________1084______13,000
65T_____________930______11,160 (estimate)
75T_____________806_______9670 (estimate)
85T_____________714_______8571
Cheers
Nick